SHEKHAR, Chander; KAUSHIK, Shiv Kumar. Perturbations of Operator Banach frames in Banach spaces. Armenian Journal of Mathematics, Yerevan, Armenia, v. 8, n. 2, p. 104–119, 2012. Disponível em: https://armjmath.sci.am/index.php/ajm/article/view/128. Acesso em: 4 apr. 2025.